[Dovecot] 1.0-stable loses flag changes sometimes?

[Chris Wakelin]

I've been struggling with an odd bug in the latest 1.0-stable 
(20050427) release. Sometimes Dovecot seems to forget that a message 
has been read or deleted and marks it unread (or not deleted).

As far as I've been able to determine, it seems to happen when
1) There have been several recent deliveries
2) Possibly some of those deliveries are of multiple messages
3) Possibly they are read very quickly (say only a second for each 
message)
4) Folder is an mbox (haven't tried Maildir)

I've seen it with Thunderbird mostly, but did manage to recreate it 
once in "telnet" - the debug IMAP client ;) - using "IDLE" "FETCH" and 
"STORE msgid +FLAGS (\Seen)" commands.

I managed to catch it in the act with one Thunderbird session, and it 
seemed to occur when Thunderbird, for some reason, issued an IMAP 
"CHECK" command. In this case it issued an extra "* 710 FETCH (FLAGS 
(\Recent))" response (the new messages had been msgid 711-715). 

Incidentally, Thunderbird seems to do a "STORE .. +FLAGS (\Seen)" 
command even though this is implicit the "FETCH .. BODY[..]" command 
(and it gets informed of the flag change in the response).

I've tried and tried to find a "formula" for re-creating the problem 
"on demand", but it only goes wrong occassionaly.

My guess is it's some sort of timing thing with mbox sync (BTW we have 
"mbox_dirty_syncs = yes" and "mbox_very_dirty_syncs = no").

Has anybody else seen this?

I'm hoping to roll out this version to our wider group of testers soon 
and would like to get this issue solved first if possible (it counts as 
an annoyance rather than a serious problem).

Best Wishes,
Chris

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Christopher Wakelin,                                c.d.wakelin at reading.ac.uk
IT Services Centre, The University of Reading,       Tel: +44 (0)118 378 8439
Whiteknights, Reading, RG6 2AF, UK                   Fax: +44 (0)118 975 3094